Fleas

Question 1

What are fleas?

Answer 1

small wingless ectoparasites of the order Siphonaptera

Question 2

Where are fleas found?

Answer 2

Live on the host or in the host’s burrow 94% of species are parasites of mammals and 6% are parasites of birds

Question 3

What do fleas vector ?

Answer 3

Plague Murine typhus Tape worms Both males and females are vectors

Question 4

How are fleas classified?

Answer 4

Combed - cat and dog fleas Combless - Pulex (human flea) and Xenopsylla (tropical rat5 flea) Jigger/ Chigoes - Tunga penetrans (not a vector)

Question 5

What are the key features of Ctenocephalides

Answer 5

genal comb pronotal comb meral rod

Question 6

What is not present in Pulex

Answer 6

No combs No meral rods

Question 7

Flea life cycle

Answer 7

Females lay eggs in the nest of host animal Larva feeds on near detritus and undergoes three moults to reach the pupal stage The pre-emergent adult can remain in the pupal state for over a year but in ideal conditions emerges after 6 days Females lay up to 25 eggs per day and can live for several months

Question 8

Where can plague be found in wild reservoirs

Answer 8

Asia, Americas and Africa

Question 9

What is Plague

Answer 9

zoonotic disease of wild rodents transmitted by numerous wild rodent fleas

Question 10

what is sylvatic plague

Answer 10

woodland plague with background levels of transmission with little harm to rodents and occasional transmission to humans (hunters and forestry workers etc.) infrequent epizootics in wild rodents and when rodents die often leads to the disease entering an urban cycle

Question 11

What is urban plague

Answer 11

First sign of urban plague in brown/sewer rat Rattus norvegicus - lives at interface between syllabic and domestic environment May be followed by an epizootic in the more domestic black rat Rattus rattus Fleas rapidly abandon dead hosts to seek out new ones Two weeks later there are human cases

Question 12

What are the main flea vectors of urban plague

Answer 12

Xenopsylla cheopis Nosopsyllus fasciatus Pulex irritans

Question 13

How is flea to mammal transmission achieved?

Answer 13

Regurgitation of fleas oesophageal contents Proventriculus - spines normally press together to prevent regurgitation Proventriculus blocked by large number of bacilli Hungry fleas then bite repeatedly

Question 14

Murine typhus - Rickettsia typhi

Answer 14

rickettsial disease also called endemic or flea borne typhus rarely fatal (<2% of cases) caused by infection of commensal rodents - Rattus rattus and Rattus norvegicus distribution throughout the tropics especially in ports transmitted through flea faeces (rubbed into the wound) Main vector is Xenopsylla cheopis

Question 15

What is the main vector of murine typhus

Answer 15

Xenopsylla cheopis

Question 16

Where is murine typhus found

Answer 16

tropics in ports

Question 17

how is murine typhus transmitted

Answer 17

flea faeces rubbed into the wound

Question 18

What are the symptoms of rickettsial disease

Answer 18

fever transient rash falling blood pressure headache backache

Question 19

Cestodes - Dipylidium caninum - dog/cat parasite life cycle

Answer 19

tapeworm eggs in animal excreta consumed by larval fleas become infective stage (cysticercoids) in adult flea infected flea eaten by dog or cat when grooming children occasionally infected when playing with pets through swallowing fleas or being licked by pets with crushed flea in mouth

Question 20

Cestodes - Hymenoleptis - rat tapeworm

Answer 20

Can also infect humans

Question 21

Xenopsylla control

Answer 21

residual insecticide spraying of domestic rat runs and burrows during outbreaks, treat all dwellings <200 m of affected one range of insecticides available but resistance common for wild rodent flea, insecticide in bate boxes made of bamboo dichlorvos resin strips on container ships

insecticial control of fleas must precede or at least be coincident with rodent control

Question 22

What is the most essential feature of insecticide control of plague and murine typhus

Answer 22

MUST precede or at least be coincident with rodent control

Question 23

Rodent control

Answer 23

domestic - rodenticides e.g. warfarin amongst many others rodent chemosterilization (long term)

wild - HCN Methyl bromide gas

Question 24

Jigger flea - Chigoes - Sand flea - Tunga penetrans

Answer 24

Distribution restricted to Americas and Africa and India attacks rodents, pigs and man - female burrows into the skin common on toes and nail bed eggs extruded from 8th day - lays 100-200 eggs over 14 days (2 larval instars)

Question 25

Treatment of jigger fleas

Answer 25

Careful removal and prevention through wearing footwear

Question 26

Where can the jigger flea be found

Answer 26

Americas, Africa and India

Question 27

What is a key feature of Tunga penetrans

Answer 27

Compressed thoracic segments Females can have a distended abdomen

Question 28

Answer 28

Ctenocephalides female

combed dog and cat flea

features include meral rod, pronatal comb and genal comb

intermediate hosts for Diphylidium caninum

Question 29

Answer 29

Xenopsylla female

combless flea and most important for plague transmission

tropical rat flea

Question 30

Answer 30

Pulex female - human flea

no combs or meral rods

important for plague transmission

Question 31

Answer 31

flea larva - maggot like and approximately 0.5 cm long

covered in many small hairs

Question 32

Distribution of countries with known presence of plague in wild reservoir species

Answer 32

Question 33

Answer 33

flea eggs - pearly white, oval with rounded ends and 0.5mm in length

Question 34

Answer 34

Flea cocoons - at the end of the larval period, the larva spins a whitish cocoon from its salivary glands - covered in dust particles

Question 35

Answer 35

tunga pentrans male

compressed thoracic segments

Question 36

Answer 36

female tunga penetrans with hugely distended abdomen

Question 37

worldwide distribution of murine typhus

Answer 37